1. Field of the Invention
The present invention relates to a hard disk drive, and more particularly, to an actuator latch device for a hard disk drive, which latches an actuator in a certain position when a disc stops rotating in order to prevent the actuator from randomly rotating due to external shocks.
2. Description of Related Art
A hard disk drive (HDD), one of the information storage devices of a computer, is a device for recording/reproducing data on/from a disc using a magnetic head. When the HDD operates, the magnetic head of the hard disk drive comes to in contact with a surface of a rotating disc after it is moved by an actuator to a desired position at a certain height from a recording surface of rotating disc.
Meanwhile, when the hard disk drive does not operate, that is, when the disc stops rotating, the magnetic head has to be parked in a position outside the recording surface of the disc so as not to impinge upon the surface of the disc. Parking systems for HDDs are of two types: a contact start stop (CSS) type and a ramp loading type. In case of the CSS type parking system, the magnetic head is parked in a parking zone where data are not recorded, which is provided at an inner circumference of the disc. In case of the ramp loading type parking system, the magnetic head is parked on a ramp installed at the outside of the disc.
However, when the magnetic head is parked in the parking zone or on the ramp, if an external shock or vibration is applied to the hard disk drive, the actuator may randomly move, and thereby separate the magnetic head from the parking zone or the ramp. In this case, the magnetic head comes into contact with the surface of the disc, and thus both the magnetic head and the surface of the disc can be damaged. Thus, when the disc stops rotating and the magnetic head is parked in the parking zone or on the ramp, the actuator must be locked in the parking position so as not to move due to an external shock or vibration. To this end, a variety of actuator latch devices have been provided.
FIGS. 1A, 1B, and 1C are views illustrating a single lever type inertia latch device as an example of a conventional actuator latch device for a hard disk drive.
Referring first to FIG. 1A, an actuator 10 is installed in the hard disk drive so as to move a magnetic head for data reproducing and recording to a desired position on a disc. The actuator 10 includes a swing arm 12 rotatably coupled to a pivot 11, and a suspension 13 installed to one end of the swing arm 12 to support a slider 14 where the magnetic head is mounted. The suspension 13 resiliently biases the slider 14 toward the surface of the disc.
Further, an inertia latch device 20 is provided in the hard disk drive to lock the actuator 10 in a state where the magnetic head is parked on the ramp 15. The inertia latch device 20 includes one latch lever 21 rotating due to an inertia force, a latch hook 22 provided at a leading end of the latch lever, a notch 23 provided at the swing arm 12 of the actuator 10, a crash stop 24 restricting a clockwise rotation of the swing arm 12, and a latch stop 25 restricting a clockwise rotation of the latch lever 21.
When a clockwise rotational shock is applied to the hard disk drive, as illustrated in FIG. 1B, the swing arm 12 of the actuator 10 and the latch lever 21 rotate counterclockwise due to an inertia force so that the latch hook 22 is engaged with the notch 23, preventing rotation of the swing arm 12 of the actuator 10. Conversely, when a counterclockwise rotational shock is applied to the hard disk drive, as illustrated in FIG. 1C, the swing arm 12 of the actuator 10 and the latch lever 21 rotate clockwise due to an inertia force. Here, the swing arm 12 rotates firstly clockwise and secondly counterclockwise while impinging upon the crash stop 24 and rebounding therefrom, and the latch lever 21 also rotates counterclockwise while impinging upon the latch stop 25 and rebounding therefrom. Accordingly, the latch hook 22 interferes with the notch 23, thereby locking the actuator 10.
The single lever type inertia latch device 20 operates accurately when a clockwise rotational shock is applied to the hard disk drive such that the swing arm 12 of the actuator 10 rotates counterclockwise. However, when a counterclockwise rotational shock is applied to the hard disk drive, if rebounding timings of the swing arm 12 and the latch lever 21 do not coincide, the notch 23 of the swing arm 12 is not engaged with the latch hook 22 and the actuator 10 is not locked. Thus, it is difficult to securely lock the actuator 10.
FIGS. 2A, 2B, and 2C are views illustrating a dual lever type inertia latch that can prevent the above problem.
Referring first to FIG. 2A, an inertia latch device 40 for locking an actuator 30 includes respective first and second latch levers 41 and 42 rotating due to an inertia force, a latch pin 43 provided at the first latch lever 41, a latch hook 44 provided at the second latch lever 42, a notch 45 provided at a swing arm 32 of the actuator 30, and a crash stop 46 restricting a clockwise rotation of the swing arm 32.
If a clockwise rotational shock is applied to a hard disk drive including the dual lever type inertia latch device 40, as illustrated in FIG. 2B, the swing arm 32 of the actuator 30 and the respective first and second latch levers 41 and 42 rotate counterclockwise due to an inertia force so that the latch hook 44 is engaged with the notch 45, preventing rotation of the swing arm 32 of the actuator 30. Conversely, if a counterclockwise rotational shock is applied to the hard disk drive, as illustrated in FIG. 2C, the swing arm 32 of the actuator 30 and the first latch lever 41 rotate clockwise due to an inertia force. Here, the swing arm 32 rotates firstly clockwise and secondly counterclockwise while impinging upon the crash stop 46 and rebounding therefrom. The latch pin 43 interferes with the second latch lever 42 that rotates counterclockwise while the first latch lever 41 rotates clockwise. Accordingly, the latch hook 44 of the second latch lever 42 interferes with the notch 45 to restrict the counterclockwise rotation of the swing arm 32.
The conventional dual lever type inertia latch device 40 operates stably when clockwise and counterclockwise rotational shocks are applied to the hard disk drive. However, it requires two of latch levers 41 and 42 so that a structure thereof is complicated and an installation space is large due to its size, thereby causing problems in that manufacturing cost and assembly time are increased, and that it is difficult to be used for a small size mobile disc drive.